Conventionally, as one mode of a tractor, there has been known a tractor in which a clutch housing and a transmission casing are connected with each other by way of a shaft support wall forming body, and various kinds of power transmission shafts are laterally extended between the clutch housing and the transmission casing in a state that the various types of power transmission shafts penetrate the shaft support wall forming body (for example, Japanese Patent Laid-open 2002-127766).
Further, a clutch is arranged in a front portion of the inside of a clutch housing, a main transmission mechanism is arranged in a rear portion of the inside of the clutch housing, a sub transmission mechanism is arranged in a front portion of the transmission casing, and a differential gear mechanism is arranged in a rear portion of the transmission casing.
Here, a rear-end peripheral portion of the clutch housing, a peripheral portion of a shaft-support-wall forming body and a front-end peripheral portion of the transmission casing are connected with each other by integrally fastening together using a connecting bolt which has an axis thereof extended in the fore-and-aft direction.
Here, in the above-mentioned tractor, the rear-end peripheral portion of the clutch housing, the peripheral portion of the shaft-support-wall forming body and the front-end peripheral portion of the transmission casing are connected with each other by integrally fastening them together using the connecting bolt which has the axis thereof directed in the fore-and-aft direction and hence, when the sealing property between the rear end surface of the clutch housing and the front-face peripheral portion of the shaft-support-wall forming body and the sealing property between the rear-surface peripheral portion of the shaft-support-wall forming body and the front end surface of the transmission casing are not favorably ensured, there arises a drawback that the leaking of oil occurs.
Further, in connecting the clutch housing, the shaft-support-wall forming body and the transmission casing together, it is necessary to perform the connecting operation such that parts which are arranged in the inside of the clutch housing and the inside of the transmission casing are respectively preliminarily assembled and, thereafter, the clutch housing, the shaft-support-wall forming body and the mission case are fastened together using the connecting bolt in a state that the clutch housing, the shaft-support-wall forming body and the transmission casing are respectively and individually supported, whereby the connecting operation becomes extremely cumbersome.